1. Field of the Invention
This invention relates to a lens mount for a TV camera, and more particularly to a lens mount for a TV camera which permits lenses having different types of mounts to be mounted on the TV camera.
2. Description of the Related Art
Generally a large-sized lens is mounted on a large-sized TV camera which is generally placed on a truck with casters and used in a limited space like a TV studio and a small-sized lens is mounted on a small-sized TV camera which is generally used on a cameraman's shoulder as a portable camera in a site including the open field.
As shown in FIG. 1B, the small-sized lens 20' is generally mounted on the small-sized TV camera 10' by way of a bayonet mount comprising a pair of bayonet rings 21 and 12 respectively fixed to the lens 20' and the camera 10' for the purpose of easiness in changing the lens. The bayonet ring 21 on the side of the lens 20' is provided with a cylindrical projection 22 which is smaller in diameter than the bayonet ring 21 and extends rearward in the direction of the optical axis L. The projection 22 functions as a locator for aligning the optical axes of the lens 20' and the camera 10' with each other. That is, the camera 10' is provided with an insertion hole 12a which has an inner diameter substantially equal to the outer diameter of the projection 22 and into which the projection 22 is telescopically inserted. When the lens 20' is mounted on the camera 10', the projection 22 is first inserted into the insertion hole 12a with the optical axes L of the camera 10' and the lens 20' in alignment with each other and then the bayonet rings 12 and 21 are brought into engagement with each other.
Since the large-sized lens 20 (FIG. 1A) is sometimes mounted on the small-sized TV camera 10', the large-sized lens 20 is also provided with a bayonet ring 21 and a projection 22 similar to those for the small-sized lens 20'.
As shown in FIG. 1A, the large-sized lens 20 is generally mounted on the large-sized camera 10 by way of hook mounts 24 and 11 provided respectively on the rear end face of the lens 20 and the front end face of the camera 10. When mounting the lens 20 on the camera 10, the hook mount 24 on the lens 20 is first brought into engagement with the hook mount 11 on the camera 10 with the front portion of the lens 20 held high and then the lens 20 is swung downward about the hook mounts 24 and 11 as shown by arrow R. Thereafter the lens 20 is fixed to the camera 20 with the optical axes L in alignment with each other. Since the large-sized lens 20 is mounted on the large-sized camera 10 by way of the hook mounts 24 and 11, the large-sized camera 10 is not provided with a bayonet ring and in order to prevent the bayonet ring 21 and the projection 22 from interfering with the large-sized camera 10, a recess 15 for accommodating the bayonet ring 21 and the projection 22 is provided on the front end face of the camera
However the small-size lens 20' is sometimes to be mounted on the large-sized camera 10. In such a case, since the small-sized lens 20' is not provided with a hook mount, a bayonet adapter (not shown) which can be engaged with the bayonet ring 22 on the small-sized camera 20' is screwed on the large-sized camera 10.
This system is disadvantageous in that the bayonet adapter must be screwed on and off the large-sized camera 10 every time the type of mount to be mounted on the camera changes, which is very troublesome. Further there is a fear of the bayonet adapter getting lost.